This study prepared samples with femtosecond(fs)-laser-induced periodic surface structures (LIPSSs) controlled by laser power (or peak fluence, F0) and overlap ratio (OR) to improve the friction and wear behavior of the SKD 61 tool steel sliding against a hard Si3N4 ceramic counterface in oil lubrications. Pin-on-plate (pin: Si3N4; plate: SKD 61 steel) tribological tests were conducted with the reciprocating motion perpendicular to the laser scanning direction and having an incline angle (40°∼50°) with respect to the LIPSSs. The contact angles (θ) formed on the textured surfaces were measured for an oil lubricant. The (θ)oil results were found to have their correlation with the areal surface roughness (Sa), skewness (Sk), and kurtosis (Ku) of the textured surfaces produced at various F0 and OR values. The mean friction coefficient (μ) and wear loss (W) of the steel specimens in oil lubrications are reduced by decreasing contact angle, (θ)oil. The combined effect of F0 and OR on the (θ)oil and the (θ)oil effect on μ and W are thus linked together, and the correlation provides an efficient and convenient way in the choices of laser operating conditions with the minimum μ and W. The minimum values of μ (=0.0089) and W (=2.124 × 104 μm3) were obtained with OR = 50% and a laser power of 17 mW.
All Science Journal Classification (ASJC) codes
- Process Chemistry and Technology
- Surfaces, Coatings and Films
- Materials Chemistry